The objective of this research project is the identification of immunologically distinct subgroups present on the capsular antigen of N. meningitidis group C. This is to be accomplished by the isolation of capsular antigens from multiple group C organisms obtained both from case and carrier strains. These capsular antigens will then be used as immunogens in rabbits. The antisera produced will be employed as reagents in immunologic test systems using cross absorptive methods to determine if distinct subgroups exist within these capsular polysaccharides. Concomitant with the immunologic studies biochemical analysis of these antigens will be performed to determine if subgroups differences within these polysaccharide antigens can be distinguished by chemical methods.